Download NERVE INJURIES OF THE LOWER EXTREMITY STACY RUDNICKI, MD ASSOCIATE PROFESSOR OF

NERVE INJURIES OF THE LOWER
EXTREMITY
STACY RUDNICKI, MD
ASSOCIATE PROFESSOR OF
NEUROLOGY
Dermatomes of the Leg
Root Innervation of the Leg
• Hip Flexion
– L 1, 2, 3
• Knee Extension
– L 2, 3, 4
• Foot Dorsiflexion
– L 4,5
• Foot Plantar Flexion
– S1, 2
• Knee Flexion
– L5, S1, S2
• Hip Extension
– L5, S1, S2
Clinical Principles
• Detecting subtle weakness
– Get up from squat
• Quadriceps/Gluteus maximus
– Stand on tip toes
• Gastrocnemius/Soleus
– Stand on heels
• Tibialis Anterior
Reflexes
• Knee Jerks - evaluates
– Quadriceps muscle
– Femoral Nerve
– Primarily L4 nerve root (also L2, L3)
• Ankle Jerk - evaluates
– Gastrocnemius muscle
– Tibial Nerve
– Primarily the S1 nerve root (also S2)
CASE 1
History
• 20 yo college student involved in an MVA
• She suffers multiple pelvic fractures
• She complains of weakness and numbness of
the right leg
• She is aware that her right foot is “dropped”
relative to the left, and that she must lift her
foot up higher to clear her toes
Exam
• She has weakness of:
– Foot dorsiflexion
– Foot eversion
– Toe extension
• Strength is normal in:
– Foot plantar flexion
– Foot inversion
– Toe flexion
• There is just a hint of weakness in knee flexion
SENSORY LOSS
Localization
Finding
Involved
Ft Dorsiflex
Grt toe ext
Toe ext
Foot eversion
Knee flex
Spared
Foot plant flex
Toe flex
Foot inv
Muscle
Nerve
Root
TIB ANT
EHL
EDL, EDB
FIB L, B
Mult
FIB
FIB
FIB
FIB
TIB/Fib
L4,5
L5
L4,5
L4,5
L5S1S2
GASTROC, TIB
SOLEUS
FDL/FDB
TIB
POST TIB TIB
S1,2
L5,S1
L4,5
Localization
Finding
Involved
Ft Dorsiflex
Grt toe ext
Toe ext
Foot eversion
Knee flex
Spared
Foot plant flex
Toe flex
Foot inv
Muscle
Nerve
Root
TIB ANT
EHL
EDL, EDB
FIB L, B
Mult
FIB
FIB
FIB
FIB
TIB/Fib
L4,5
L5
L4,5
L4,5
L5S1S2
GASTROC, TIB
SOLEUS
FDL/FDB
TIB
POST TIB TIB
S1,2
L5,S1
L4,5
Common Fibular (Peroneal) Nerve
Common Fib
Short head BF
Deep Fib
Superficial Fib
Fib Longus
Fib Brevis
Tib Ant
EHL
Fib Tertius
EDB
Differentiating b/w L5 radiculopathy and
Fibular Neuropathy
• Motor exam
– Foot inversion - Posterior tibial muscle
• Spared - Fibular neuropathy
• Involved - L5
• Sensory exam
Sensory loss in deep fibular, common
fibular, and L5 disease
Final Diagnosis
Sciatic neuropathy with selective
involvement of the fibular (peroneal)
nerve fibers at the level of the pelvis
Pearl: The fibular component of the
sciatic nerve is more susceptible to
traumatic injury than the tibial
component - “false localization”
CASE 2
History
• The patient is a 45 yo man who complains of
burning pain in his right lateral thigh
• He is otherwise healthy, though over the last 2
years, he has gained 30 pounds because he
can’t find time to exercise
Exam
• He has normal strength in all muscles of his leg
• Reflexes are normal
SENSORY LOSS
Localization
Finding
Muscle
Nerve
Root
Sens loss
--
Lat fem
cut
<<L2
Final diagnosis
Lateral femoral cutaneous neuropathy
(AKA: Meralgia Parasthetica)
Pearls:
This nerve does not come from the
femoral nerve but rather the L-S plexus
 There is no motor component
 It is trapped as it crosses the pelvic
brim, and wt loss or gain can precipitate
sxs
CASE 3
History
• A 27 yo man is shot at multiple sites in the
thigh, popliteal fossa, and foot
• He complains of burning pain in the foot and
weakness of the foot
Exam
• He has weakness of:
– Foot plantar flexion
– Foot inversion
– Toe flexion
• Strength is normal in:
– Knee flexion
– Foot dorsiflexion
– Foot eversion
• His foot has a “cocked up” appearance and is
everted compared to the other foot
SENSORY LOSS
Exam
Finding
Involved
Ft plant flex
Toe flex
Foot inv
Sens loss
Spared
Ft dorsiflex
Foot ever
Knee flex
Muscle
PN
Root
GASTROC
FDL, FDB
POST TIB
----
TIB
TIB
TIB
MP+LP (tib)
S1, S2
L5, S1, S2
L4, L5
<S1
TIB ANT
FIB L, B, T
HS SHBF
FIB (per)
L4,5
FIB (Per)
L5S1
SCIATIC
L5, S1, S2
(Tib and Fib)
Exam
Finding
Involved
Ft plant flex
Toe flex
Foot inv
Sens loss
Spared
Ft dorsiflex
Foot ever
Knee flex
Muscle
PN
Root
GASTROC
FDL, FDB
POST TIB
----
TIB
TIB
TIB
MP+LP (tib)
S1, S2
L5, S1, S2
L4, L5
<S1
TIB ANT
FIB L, B, T
HS SHBF
FIB (per)
L4,5
FIB (Per)
L5S1
SCIATIC
L5, S1, S2
(Tib and Fib)
Sciatic Nerve in Thigh/ Tibial Nerve in Leg
Sciatic Nerve
Semitendonous
Semi Membranous
Add Magnus
Tibial Nerve
Gastroc, Med
Soleus
Tibialis Post
FDL
Med Plantar
AH, FDB, FHB
Biceps Long Hd
Biceps Short HD
Common Fib Nv
Popliteus
Gastroc, lat
FHL
Lateral Plantar
ADM, FDM, AH, Int
Final Diagnosis
Tibial neuropathy at the popliteal fossa
Pearl:
The appearance of the foot at rest may
help distinguish b/w a fibular and a
tibial neuropathy - unopposed action of
spared muscles
CASE 4
History
• An 81 yo man with diabetes mellitus complains
of onset of deep aching pain in his right thigh
that evolved over a few weeks
• He is having trouble walking because his knee
“gives out”
• He complains of numbness on the top of his leg
Exam
• He has weakness of:
– Hip flexion
– Knee extension
• He has normal strength of:
– Hip adduction
– Hip abduction
– Foot dorsiflexion/plantar flexion
• His knee jerk is absent, his ankle jerk is
preserved
SENSORY LOSS
Localization
Finding
Hip flex
Knee Ext
Sens Loss
Hip Add
Hip Abd
Foot DF
Foot PF
Muscle
IP/Rec Fem
Quads
--ADD L, B, M
Add M
Gl Med/Min
Tib ant
Gastroc/sol
PN
Fem
Fem
Fem
Obt
Sciatic
Sup Glut
Fib (Per)
Tibial
Root
L1,2,3
L2,3,4
L2-4
L2,3,4
L5, S1
L5, S1, S2
L4,5
S1,S2
Localization
Finding
Hip flex
Knee Ext
Sens Loss
Hip Add
Hip Abd
Foot DF
Foot PF
Muscle
IP/Rec Fem
Quads
--ADD L, B, M
Add M
Gl Med/Min
Tib ant
Gastroc/sol
PN
Fem
Fem
Fem
Obt
Sciatic
Sup Glut
Fib (Per)
Tibial
Root
L1,2,3
L2,3,4
L2-4
L2,3,4
L5, S1
L5, S1, S2
L4,5
S1,S2
Femoral nerve
Iliopsoas
Sartorius
Rectus Femoris
Vastus Lat
Vastus inter
Vastus Med
Pectinius
Distinguishing b/w a femoral neuropathy
and L2 or L3 radiculopathy
• Motor exam
– Thigh adduction (obturator nerve)
• Spared with a femoral neuropathy
• Involved with L2,3 disease
• Sensory exam
– Loss extends below the knee (medial foreleg)
with femoral neuropathy
• Saphenous nerve
Final Diagnosis
Femoral Neuropathy Related to Diabetes
Mellitus
Pearl:
The femoral nerve is also liable to injury
during procedures involving the femoral
artery or vein
CASE 5
History
• A 27 yo body builder complains of a 4 week
history of low back and leg pain
• Pain travels down the back of the leg and into
the sole of the
• He is unaware of weakness and he continues to
lift weights
Exam
• His routine strength exam is normal
• He can stand on his heels with ease
• He can stand on his tiptoes on the right but not
on the left
• His left ankle jerk is absent, right is normal
• Sensory exam
– Decreased sensation of the sole of the foot, lateral
distal leg, and lateral dorsum of the foot
Localization
Finding
Muscle
PN
Stand toes
Abs AJ
Sens
GASTROC/SOL TIB
S1,2
GASTROC/SOL TIB
S1,2
--MP, LP, SU S1
Stand Heels
Foot Inv
TIB ANT
POST TIB
FIB
TIB
Root
L4,5
L4,5
Localization
Finding
Muscle
PN
Stand toes
Abs AJ
Sens
GASTROC/SOL TIB
S1,2
GASTROC/SOL TIB
S1,2
--MP, LP, SU S1
Stand Heels
Foot Inv
TIB ANT
POST TIB
FIB
TIB
Root
L4,5
L4,5
Differentiating b/w radicular disease and
focal tibial neuropathy
• Back pain that radiates into the leg highly
suggestive of radicular process
• Tibial nerve also innervates the foot inverters
yet these are spared
• Spontaneous (ie not associated with
penentrating trauma) tibial neuropathies
would be very unusual
Final diagnosis
S1 radiculopathy related to a herniated
disc
Pearl:
 The term sciatica is a misnomer - it is
really a root based process, not one of
the sciatic nerve
 Particularly in large muscles,
weakness may be subtle and hence easily
missed
Final Comments
• Overall, nerves in the leg are less liable to
chronic compression/entrapment compared to
those in the arms
• Most common entrapment in the leg is a fibular
(peroneal) palsy at the fibular head
– May get the common, superficial, or fibular
(peroneal) nerve
• Traumatic nerve injuries related to penetrating
injury / bony trauma (hip / pelvic fxs) are seen